Screening for urinary tract infection was carried out in 27,722 schoolboys aged 5 to 14 using Uricult to perform urine cultures and Hema-combistix to detect hematuria, proteinuria and glycosuria. Cultures of 10(5) colonies per ml or more on two occasions were found in 40 cases (0.14%), but no case was confirmed by the family physician using standard culture techniques.Proteinuria was found in 136 cases (0.49%) and confirmed in 47 (37%) of the 126 children who were seen by their family physician. In this group 8.8% had evidence of pyelonephritic scarring on intravenous pyelograms without a positive urine culture.Hematuria was found in 19 children and confirmed in 10 (59%) of the 17 children who were seen by their family physician. No abnormalities were detected on intravenous pyelography in any case.Glycosuria was found in 12 cases and confirmed in five. Three of these children had renal glycosuria and two had previously undetected diabetes.